1. Field of the Invention
This invention relates to a single magnetic pole head used as a recording head in a perpendicular magnetic recording system. More particularly, it relates to a thin-film single magnetic pole head in which the main magnetic pole is formed by a soft magnetic thin film.
2. Description of the Related Art
In the field of magnetic recording, such as in a hard disc or a floppy disc, recording density is increasing drastically, such that 1 Gbit/square inch or even 10 Gbit/square inch is not unlikely to be reached.
In magnetic recording system, so-called longitudinal recording system (in-plane recording system) is customary, and a longitudinal recording medium is routinely used for recording/reproduction. If the recording density reaches the order of 10 Gbits/square inch, recording demagnetization poses a problem because the diamagnetic coefficient is increased in the case of the longitudinal recording medium.
Also, for high recording density, the recording frequency needs to be increased, such that, in a recording head, it is necessary to decrease the inductance in order to decrease the rise time of the writing current waveform. Although it is attempted to form the recording coil in two layers, such attempt occasionally leads to a complicated process.
Under these circumstances, attention is again directed to the perpendicular magnetic recording system, which can maintain stable magnetization despite high recording density.
In the perpendicular magnetic recording system, there is required a magnetic head capable of recording on a perpendicular magnetic recording medium. For example, in a single-layer perpendicular magnetic recording medium, writing is possible by a so-called ring head. However, with a double-layer perpendicular magnetic recording medium, having a high magnetic permeability layer below the magnetic layer, recording characteristics in a higher frequency are deteriorated because of recording demagnetization, although recording is possible with the ring head. Thus, there is raised a demand for a recording head exhibiting superior recording characteristics even in a high frequency range.
In order to meet the demand for improved recording density, high resolution is achieved by increasing coercivity and reducing the film thickness. In a recording head, there have been attempts to increase saturation density of a recording core and to increase frequency characteristics of magnetic permeability of a recording core material, in order to cope with increased coercivity of a recording medium, while attempting to establish a manufacturing method for a narrow track head and to provide a double-layer recording coil in order to cope with high track density and in order to reduce head inductance to cope with the high linear recording density.
Although there have been attempts to reduce the film thickness of the main magnetic pole in the magnetic head of the perpendicular magnetic recording system, it is necessary to energize the foremost part of the main magnetic pole with high efficiency.
Notwithstanding past efforts to improve the recording head in this line, there has not been found a practically satisfactory head structure.